Heating apparatus



Nov. 7, 1944. s. E. HEYMANN 2,362,271

HEATING APPARATUS Filed Nov. 16. 1942 2- Sheets- Sheet 1 v Nov. 7, 1944.s. E. HE YMANN 2,362,271

HEATING APPARATUsL Filed Nov. 16; 194? 2 Sheets-Sheet 2 Patented Nov. 7,1944 UNITED STATES PATENT OFFICE HEATING APPARATUS Seymour Heymann,Chicago, Ill., assignor to Stewart-Warner Corporation, Chicago, 111., acorporation of Virginia Application November 16, 1942, Serial No.465,673 Claims. (Cl. 257-241) My invention relates to heating apparatusand more particularly to a. hollow fin type of heat exchanger adaptedfor use either as part of an internal combustion heater or as part oi.an exhaust heater which is supplied with hot gases of combustion 'froman internal combustion engine or other source.

In exhaust heaters and in heaters of the in-' ternal combustion type, itis common to provide finned heat transfer means for transferring heatfrom the products of combustion to the ventilating air directed over theheat transfer means by a ram, blower or any other means for circulatingair. The hot gases of combustion come in more intimate contact with thebases of the fins and create hot spots therein, which are at atemperature greatly in excess of the temperature of otherportions of theheat exchanger. There is a. practical limit to the temperature to whichthe fins can be heated and since the hot spots can not be raised abovethis practical limit, the greater portion of the heat exchanger ismaintained at a temperature considerably below this limit.

An object of my invention is to provide new and improved heatingapparatus which eliminates these hot spots and which makes it possipleto operate the heat exchange means at a more uniform and higher averagetemperature to pro-,

vide a more efficient heater having a higher heat output for agivensize.

Another object of my invention is to provide a heaterwherei'n thetemperature range between different parts of the heater is reduced to aminimum and stresses and strains caused by great variations intemperature of the different parts are avoided.

Another object of my invention is to provide an extremely light andcompact heater having a high heat output and particularly adapted foruse in aircraft.

Another object of my invention is to provide a heat exchanger which canbe manufactured by a novel and simplified method.

Other objects and advantages will become apparent as the descriptionproceeds.

In the drawings:

Fig. l is a longitudinal, sectional view through an internal combustiontype of heater embodying a preferred form of my invention. This view istaken on the line |-l 01' Fig. 2.

Fig. 2 is a transverse, vertical section taken on the line 2-2 of Fig.1-;

Fig. 3 is a perspective view of a preliminary step in forming the ringsfrom which my new and improved heat exchanger is made Fig. 4 is a viewsimilar to Fig. 3, but showing the completed ring;

Fig. 5 is aperspective View of an exhaust heater embodying my invention;and

Fig. 6 is a view showing a longitudinal section through a portion of theexhaust heater of Fig. 5.

In Figs. 1 and 2 of the drawings, I have illustrated an internalcombustion type of heater having a combustion chamber In supplied with acombustible mixture from any suitable source and forced into thecombustion chamber with sumcient pressure to create the necessary flowof combustible mixture into the heater and gases of combustiontherefrom. The combustible mixture supplied to the combustion chamber i0is ignited by one or more electrical igniters l2 which may be providedwith the usual thermostatic switch for disconnecting these igniters'fromtheir source of current when the heater has attained normal operatingtemperature. A re-igniter l4 thereafter serves to maintain combustion ofthe mixture supplied to the combustion chamber.

The hot products of combustion flow from the combustion chamber 10 intothe tapered passage l6 formed between the inclined upper wall l8 of amufiler 2lliand the upper portion of a tubular heat exchanger '22. Theheat exchanger 22 has a plurality of annular hollow fins 24 having in-.ermost portions of the passages 26 and conducts these gases to anoutlet chamber 32 which is connected by means of an outlet fitting 34 toany suitable exhaust pipe leading to atmosphere.

The muffler 20 has a shell 35 of sheet metal or other suitable materialwhich encloses sound absorbing and heat resistant material 38, such, forexample, as stainless steel wool or glass wool. The shell 36 isprovidedwith a multiplicity of small openings 40 connecting the interiorof the mufiier shell with the gas passages 26 and forming acousticcouplings through which sound may pass from the gas into the interior ofthe muflier and there be absorbed by the glass wool orother material 38.l v

The heat exchanger 22 is enclosed in a casing 42 having a cylindricalbody ll closely fitting about the exterior of the heat exchanger. The

casing 42 has an inclined inlet 46 provided with an inlet opening '48which is adapted to project into the air stream flowing along the wallof an airplane cabin or similar surface and acts as a ram to produce aflow of ventilating air through the casing 42. The ventilating airdirected into the inlet 46 is distributed among the air passages 50formed between the hollow flns 24 and flows downwardly in the oppositesides of these passages to the tapered outlet duct 52 from whence theheated air is discharged through an outlet opening 54 into the airplanecabin or other space to be heated. The casing 42 may be made of thinsheet metal or other relatively light and inexpensive material which caneasily be fabricated to assume the form shown in the drawings.

The heat exchanger 16 is formed of a plurality of rings 56 having theconfiguration best shown in Fig. 4. Each of these rings has a side 58, a

tip portion 60, and a base portion 62 The tip portion is provided with aradially extending flange 64 and the base portion is providedwith asimilar flange 66. The heat exchanger is formed by juxtaposing aplurality of rings 56 in the arrangement shown in Fig. 1 and securingadjacent flanges to each other by seam welding or in any other suitablemanner.

The individual rings 56 are preferably formed of sheet metal such, forexample, as stainless steel or any other suitable material and areformed by cutting and stamping annuli of sheet temperatures attained bythe other portions of the heat exchanger. The flanges 64 also increasethe dissipation of heat from the tips of the fins and I have shown thefln tips as being broader .than the bases to provid a more uniformtemperature throughout the heat exchanger. The-shape of the flns and thesizes of the flanges 64 and 66 may be varied .to satisfy diflerentconditions of operations. The tip flanges 84 and base flanges 66 alsoincrease the rigidity of the heat exchanger and make it possible to formthis heat exchanger of extremely thin material which is highly eflicientin the transfer of heat from the burned gases to the ventilating air. I

In Figs. 5 and 6, 1 have illustrated a modified form of my inventionwherein my novel heating apparatus is utilized to transmit heat from theexhaust gases of an internal combustion engine to ventilating air. Inthisiorm or my invention, the'engine exhaust pipe 10 is connected to theinlet-end of my finned heat exchanger 12,

which may be of the same construction as the heat exchanger 22 of theprevious embodiment. The outlet end of this heat exchanger is connectedto a tail pipe 14 through which the cooled exhaust gases are dischargedto atmosphere. The heat exchanger I! is enclosed in a casing 16 havingan inlet ram I. and an outlet opening Oil communicating with theexterior of the cabin .or other space'to be heated. This casing It maycorrespond in all respects with the casing 42 o! the previousembodiment.

The embodiment of Figs. 5 and 6 is not provided with a muflier and theentire interior of the tubularheat exchanger forms a passage for theexhaust gases which flow therethrough longitudinally of the heat,exchanger. As the exhaust gases travel through the heat exchanger eddycurrents are formed in the interiors of the hollow fins, as shown by thecurved arrows in Fig. 6, and the existence of these eddy currentsinsures eflicient heat transfer from the exhaust gases to the heatexchanger which, in turn, transfers this, heat to the ventilating air.

While I have illustrated and described my novel heating apparatus asbeing utilized only in connection with internal combustion types ofheaters and with exhaust heaters, my invention is not limited to suchuse but may be utilized to transfer heat between any fluids havingdifferent initial temperatures. My invention is also not to be construedas limited to the details herein shown and described, since it mayassume numerous other forms and is to be considered as including allvariations and modifications falling within the scope of the appendedclaims.

I claim:

1. Heating apparatus, comprising a tubular heat exchanger, meansconnected to one end of said heat exchanger for supplying hot gases tothe interior Of said heat exchanger, and a casing surrounding said heatexchanger and providing a passage for ventilating air therebetween, saidcasing having a, tapered inlet terminating in an opening at one end ofthe casing and an oppositely tapered outlet terminating in an outletopening at the other end of said casing, said heat exchanger comprisinga plurality of annularly arranged hollow fins having tips and bases andannularly arranged radially extending flanges intermediam said hollowflns and integral with the bases thereof.

2. Heating apparatus, comprising a tubular heat exchanger having one endconnected to an engine'exhaust pipe for supplying hot gases to theinterior of said heat exchanger, a casing surrounding said heatexchanger and providing a passage for ventilating air therebetween, saidcasing having a tapered inlet terminating in an opening at one end ofthe casing, and an oppositely tapered outlet terminating in an outletopening at the other end of said casing, said heat exchanger comprisinga plurality of annularly arranged hollow fins having tips and bases andannularly arranged radially extending flanges intermediate said hollowfins and in heat transmitting relation with the bases thereof.

. 3. Heating apparatus comprising a combustion chamber, 'a tubular heatexchanger into which said combustion chamber discharges hot gasesotcombustion, said heat exchanger having annular hollow fins, a muiflerlocated in said heat exchanger and having inclined upper and lowerportions forming, respectively, a passage for ad-- mitting hot gasesfrom said combustion chamber to the interior of said hollow fins and tordischarging gases from said hollow fins to atmosphere, said mumer andhollow fins providing a plurality oi semi-circular passages for thegases of combustion. and a casing enclosing said heat exchanger, saidcasing having a tapered inlet e for ventilating air tapering in the samedirection as said gas inlet'passage, said casing also having-a taperedoutlet passage for ventilating air tapering in the same direction assaid gas outlet passage, said-casing and heat exchanger providing aplurality of arcuate passages for ventilating air between saidflns.

4. Heating apparatus comprising a combustion chamber, a tubular heatexchanger into which said combustion chamber discharges hot gases ofcombustion, said heat exchanger having annular hollow fins provided withflanges at their tips and bases, a, mufiler located in said heatexchanger, aid mufiler and hollow fins providing a plurality ofsemi-circular passages for the gases of combustion, and a casingenclosing said heat exchanger, said casing having a tapered inletpassage for ventilating air and a tapered outlet passage for ventilatingair, said casing and heat exchanger providing a, plurality of arcuatepassages for ventilating air between said fins.

5. Heating apparatus comprising a combustion chamber, a tubular heatexchanger into which said combustion chamber discharges hot gases ofcombustion, said heat exchanger. having annular hollow fins with annularflanges integral with their bases, a muiller located in said heatexchanger and having inclined upper and lower portions forming,respectively, a; passage for ad-' mitting hot gases from said combustionchamber to the interior of said hollow fins and for discharging gasesfrom said hollow fins to atmosphere, said mumer and hollow finsproviding a plurality of semi-circular passages for the gases ofcombustion, and a casing enclosing said heat exchanger-{said casinghaving inlet and outlet passages for ventilating air, said casing andheat exchanger providing a plurality of arcuate passages for ventilatingair between said fins.

' SEYMOUR E. HEYMANN.

